The present invention relates to a high-lift lateral dump system for pavement/street sweepers and, more particularly, to a lateral dump system that is simple in design and operationally efficient.
Various types of vehicles have been developed to sweep or vacuum debris from pavements, roadways, and streets. In general, these vehicles use a motor driven fan to create a high-velocity air flow to effectively vacuum or aspirate the debris from the pavement or street surface. In a typical vacuum system, a motor-driven fan develops a high-volume, high-velocity recirculating air-flow through an intake hood that is mounted closely adjacent the pavement surface. A gutter broom is often mounted adjacent to each lateral side of the vacuum hood to brush debris into the path of the intake hood. As the intake hood is moved along the pavement surface, debris is aspirated into the air flow and carried by ducting into and through a debris-collecting hopper or container. The velocity of the air flow is reduced in the debris container so that entrained particles xe2x80x9cdrop-outxe2x80x9d of the air flow and are collected in the debris container. When the debris container has reached capacity, the container is emptied and the sweeping/vacuum operation is resumed.
From a conceptual standpoint, different design themes have been developed relating to the issue of debris off-loading. These design themes include belly-dump systems, various types of end-dump or side-dump systems, and high-dump systems.
In the belly-dump system, doors or hatches are provided on the underside of the debris container so that, when opened, the debris is directly dumped from the vehicle. In a typical scenario, the sweeper is driven to an area specially designated for receiving the debris removed from the roadway or pavement.
In side-dump systems, the doors or hatches of the debris-container are located on a lateral side thereof and the debris container is mounted so that it can be tilted to dump the debris from the debris container. In some systems, the debris is dumped from the rear of the vehicle while, in other systems, the debris is dumped from one lateral side or the other.
The high-dump systems can be viewed as a variation of the lateral dump system in that the debris container is first lifted or elevated above its initial position and then tilted to dump the debris through the container doors. In some high-dump systems, the debris container is lifted over the vehicle cab so that the debris is off-loaded from the forward end of the vehicle, in other systems the debris container is lifted above the rear end of the vehicle, and, in lateral high-dump systems, the debris container is lifted upwardly and over the side of the vehicle to effect lateral dumping.
Lateral high-dump systems are particularly useful in the highway sweeping context in which the time-efficient off-loading of debris into a conventional dump truck is considered important. In this context, a sweeping vehicle will sweep debris until its debris container is full. At that time, a conventional dump truck will position itself in a side-to-side relationship with the sweeping vehicle. The debris container will be elevated above the upper edge of the dump truck and thereafter tilted to dump its load into the bed of the dump truck. A lateral high-dump arrangement allows relatively quick off-loading of the debris and minimizes opportunities for motor vehicle accidents when sweeping highways.
In the lateral high-dump context, it is considered important that all or almost all the debris be transferred from the debris container into the dump truck with a minimum of spillage onto the road surface. To this end, it is considered acceptable to laterally shift the debris container toward the dump truck during the dump cycle.
One company, Elgin Sweeper Co. of Elgin Ill., has designed a high-dump system that employs a fork-lift type mast that is used to elevate the debris container, as disclosed in U.S. Pat. No. 5,251,652. In addition, Elgin Sweeper also markets a high-dump system under the AirBear tradename that uses a hydraulically driven multi-link xe2x80x9cscissor-jackxe2x80x9d system to lift or elevate the debris container to its elevated position. A hydraulically operated slide arrangement is mounted on the top of the scissor-jack system and is used to shift the debris container laterally so that the debris container extends somewhat over the lateral edge of the vehicle and is better positioned to dump debris into the dump truck. When the debris container is in its elevated and laterally shifted position, the debris container is tilted to effect the dumping operation.
From a design standpoint, the scissor-jack system and its lateral slide must be mounted beneath the debris container; the vertical depth of the debris container must be reduced to accommodate the vertical height of the scissor/slide system that underlies the debris container. As a practical matter, the dimensions of the debris container that define its internal volume, including its vertical height, must be sufficiently large so that the velocity of the incoming air stream can slow sufficiently to allow the entrained particles to xe2x80x9cdrop outxe2x80x9d of the air flow for collection and still allow sufficient space for the air stream to continue through the system. The need to mount the scissor/slide system beneath the debris container requires that the vertical height of the debris container be reduced to accommodate the scissor/slide system and also requires that the volume of the debris container be reduced by as much as 30% or so.
In view of the above, it is an object of the present invention, among others, to provide a high-lift lateral dump system for pavement/street sweepers that is structurally efficient.
It is another object of the present invention to provide a high-lift lateral dump system for pavement/street sweepers that maintains the debris container in a horizontal or near-horizontal attitude as the container is lifted from its lowered to its raised position.
It is still another object of the present invention to provide a high-lift lateral dump system for pavement/street sweepers that includes a torque control system that minimizes the consequences of any mis-phased operation of the hydraulic cylinders used to effect lifting.
It is a further object of the present invention to provide a high-lift lateral dump system for pavement/street sweepers having a manual safety stop locking arrangement by which the structural components of the system can be locked in a raised position to allow the safe inspection of the system while in its raised position.
It is still another object of the present invention to provide a high-lift lateral dump system for pavement/street sweepers including an efficient door-opening and closing system by which debris can be emptied from the debris container.
In view of these objects, and others, the present invention provides a high-lift lateral dump system for pavement/street sweepers, preferably of the type having the major components thereof mounted on a commercial truck chassis. In the preferred form, the system includes a debris container for receiving debris swept from the roadway or pavement surface and a lift assembly mounted on each side of the debris container for lifting the container from a lowered, cradled position to an elevated, lift position from which the debris can be dumped or off-loaded. Each lift assembly includes a vertically aligned upright secured to the vehicle frame and a lift arm pivotally connected at one end to the upright and pivotally connected, at the other end, to the debris container. A hydraulic lift cylinder is connected between each lift arm and an anchor bracket to selectively move the lift arm and the connected debris container between its lowered and lifted positions. An attitude-control hydraulic cylinder and a tilt-control hydraulic cylinder are mounted as a tandem cylinder-set on each lift arm to control the attitude of the debris container as the lift arms are moved from their lower position to their lifted positions and to also control tilting of the debris container when in its lifted position. The attitude-control hydraulic cylinder functions to maintain the debris container in a horizontal to substantially horizontal position as the debris container is lifted from the lowered position to the lifted position. The tilt-control hydraulic cylinder is selectively actuatable by an operator to further rotate the debris container about its pivotal connection with the lift arm to an inclined attitude sufficient to dump debris from the debris container when the debris container is in its lifted position.
In accordance with one feature of the invention, the attitude-control hydraulic cylinder is in fluid communication with its lift cylinder and receives a flow of pressurized fluid from its lift cylinder when the lift cylinder is moving the respective lift arm from the lowered position to the lifted position to automatically maintain the attitude of the debris container in a horizontal or near horizontal position during the lift sequence.
The system is provided with a torque-control system connecting the lift arms to one another throughout the lift cycle to accommodate any mis-phased operation of the lift cylinders. The torque control system includes a rotatably mounted and axially extending torsion bar having axially spaced torque arms. Each torque arm is connected by a respective linkage to a lift arm. The torsion bar is effective to prevent undesired twisting or torquing of the debris container in the event one lift cylinder leads or lags the other or is otherwise mis-phased during the operating cycle.
The system is provided with a manual safety stop locking feature by which the structural components can be mechanically locked in the raised or lifted position to allow an operator to inspect the system without concern as to an accidental or unintentional movement of the lift components to the lowered position. One of the linkage mechanisms that connects the torque arm of the torque control system to its respective lift arm includes a lock-pin receiving hole that co-aligns with another lock-pin receiving hole on its connected torque arm when the lift system is in its raised position. A lock pin is inserted into the co-aligned lock-pin receiving holes in order to lock the system in its lifted position.
The system also features a bi-door arrangement for the debris container which includes first and second doors and fluid-actuated door-control cylinders that selectively open and close the second door. The facing edges of the two doors are formed with a complementary xe2x80x98miteredxe2x80x99 interface so that the second door, when moved to its closed position by the door-control cylinder, also engages the first door to automatically close the first door.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description to follow, taken in conjunction with the accompanying drawings, in which like parts are designated by like reference characters.